The present invention concerns a device for adjusting a physical dimension transformed into outputs or output curves by a sensor.
A sensor for measuring physical dimensions and a method of adjusting it are known from the German Patent Publication No. A 3,446,248. This particular sensor is a pressure sensor, and a processing circuit that calculates the precise measurement is employed along with it. The sensor is combined with a constant-value memory into a single component. The memory stores values employed to correct measurement signals emitted by the sensor. Several points at which the sensor is to measure the dimensions travel in succession over a test bench. The signal emitted by the sensor is employed as an actual value in a comparator. Corrections are obtained in the form of deviations between the actual and reference values and stored in the component's memory.
There is a drawback to this procedure. The corrections can be obtained and stored only while the sensor component is open. Once they have been obtained and stored, a data-and-address bus is removed from the memory and the component is coupled to insulation. The address-and-data input terminals are no longer accessible. The encapsulation makes it necessary to re-adjust the already corrected test signals, which can no longer be corrected.
An angle-of-rotation sensor is known from the German Patent Publication No. U 9,408,516 (corresponding to PCT/EP94/03825). It is stationary and includes at least one stator and a rotor that rotates around the stator. The stator is in two parts with a gap between them. The gap accommodates an electromagnetic component, particularly a Hall-effect component, that emits a voltage representing the angle of rotation.
A speed-of-rotation sensor is known from the German Patent Publication No. A 4,445,378. It emits rectangular pulses representing the position of a shaft from stationary to the highest permissible rated speed. The standstill output signal is emitted in response to comparison of an incoming signal that represents magnetic flux density with a threshold signal.
The two latter approaches have drawbacks. The sensor voltages and thresholds are adjusted with variable resistors. The resistors, however, can be varied only while the sensor is open. If the sensor is inside some sort of vessel, it cannot be re-adjusted.